TOOLING FOR PRECISION MACHINING, FOR EXAMPLE FOR GRINDING VALVE SEATS

Abstract

The present invention relates to a tool for precision machining, for example for grinding valve seats of a heat engine. The tool according to the invention comprises a housing 2, a sleeve 3 provided with a spherical orientation nut 3a, mounted inside the housing, a one-piece machining shaft 6, mounted freely in rotation and translation within the sleeve, and a means for adjusting the height of the shaft 6, comprising a means for rotationally locking said shaft to a sleeve 17 movable in translation relative to the sleeve.

Description

Tooling for precision machining, for example for grinding valve seats The present invention relates to a tool for precision machining. sion according to the main patent, in particular for the grinding of valve seats of internal combustion engines. In accordance with the main patent, a tooling system has been described. generally comprising - a housing - a means of securing the housing to the workpiece, i.e., the cylinder head of the internal combustion engine - a sleeve equipped with a spherical orientation nut, which is mounted inside the casing; the sheath has a trans- a horizontal shaft whose axis passes through the center of the spherical nut - two seats of concave sphericity complementary to the spherical nut, arranged inside the housing, on either side of said nut - a spindle mounted freely in rotation and translation in the transverse bore of the housing; the latter includes on either side of the spherical nut respectively two openings each allowing the passage and movement of the spindle - a pilot rod coaxial to the axis of the spindle, extending the latter at one end, intended to penetrate in a fitted manner into a reference hole.that is to say the guide of a valve stem - a means of locking the sleeve in orientation - a rotating machining tool, mounted at the end of the spindle on the pilot stem side, possibly via a tool holder device - a means of adjusting the height of the spindle with pilot stem, called "taking depth", relative to the sleeve; this means is mounted on said sleeve, outside the housing, opposite the machining tool - a means of rotating drive, mechanical or manual. outside the housing and opposite the machining tool. And in combination, characteristic of the invention: a) the spindle and the pilot rod are constructed as a single unit on a single interchangeable machining shaft, comprising, depending on its height, a first part or hub forming the spindle, having a nominal diameter, and a second part of smaller diameter, forming the pilot rod; b) the part(s) of said tooling, located outside the shoe and on the side opposite the machining tool, for example the means for adjusting the height of the machining shaft, together define an extraction hole of said machining shaft, aligned along the axis of the transverse bore of the sleeve, and of a diameter at least equal to the nominal diameter; c) the means for adjusting the height of the machining shaft comprises, on the one hand, a coupling sleeve rotating with the hub of the machining shaft, movable in translation relative to the sleeve, and on the other hand, a reversible hub for locking the sleeve in rotation relative to the means, such as a screw.accessible for manipulation by the user outside the machine. Furthermore, according to the main patent, an adapter piece (9) mounted and rotationally fixed at the end of the hub or spindle (6a) of the machining shaft (6), on the side of the pilot rod (6b), and supporting a tool-holding device (10), has been described with reference to Figure 1. as well as the tool (S) itself. This device is compatible and allows the extraction of the single interchangeable machining shaft (6), pilot (6b) and / or machining tool (8), in relation to the part to be machined. Thanks to the invention according to the main patent, freedom in translation Adjusting the height of the machining shaft (6) allows not only its complete removal from the tooling, but also its height adjustment relative to the workpiece. This is achieved by loosening the screw (19) to release the shaft (6) from the coupling sleeve (17), and by releasing the rotational stop of the adapter piece (9) from the spindle (6a). The entire machining shaft (6) can then slide freely relative to the rest of the tooling and be positioned by the user at a height compatible with the position of the guide (1b) with respect to the pilot (6b) on the one hand, and with the position of the seat (1a) to be ground on the other. which relates to tool (8). Furthermore, the possibility of relative sliding between the adapter piece (9) and the spindle (6a) allows for independent or complementary adjustment of the machining tool (8) relative to the seat (la). These adjustments are made through the extraction holes (17b, 20a) for the various parts located outside the bootmaker (2). Such tools prove to be particularly easy to use or handle. pulation, in particular thanks to the possibility of extraction and interchangea- the bility of the machining shaft, and therefore of the pilot rod, while leaving the tool- The tool is positioned and fixed, for example, to the cylinder head gasket surface of the internal combustion engine or the cylinder head itself. Furthermore, this tooling provides great flexibility in adjusting or positioning the pilot rod's height relative to the valve stem guide, and / or in adjusting or positioning the pilot rod. height of the machining tool relative to the valve seat. The height adjustment mechanism (I 1), known as the "depth adjustment" mechanism, essentially allows for the gradual lowering of the machining tool as the grinding operation progresses. Its height adjustment range may be completely insufficient for positioning the tool at the correct height before or during machining, since the shank is pre-formed prior to the actual machining operation. In this case, the machining arbor can be re-secured. in rotation. with the coupling sleeve (I l), and with the adapta- trice (9). These various adjustments are further facilitated by the fact that the machining shaft (6) comprises the pilot rod as a single unit. (6b) and the pin (6a). is accessible to the user, on the one hand from the top. and on the other hand through the means of solidification (63) or base tools. The present invention relates to a variant embodiment of the adapter piece (9), facilitating the function according to the main patent, namely the rotational locking and unlocking of said piece, without affecting the intrinsic rigidity of said piece, necessary to precision machining. According to the present invention, the adapter piece has two through threaded holes arranged radially with respect to the axis of the machining shaft, forming an angle of 180° between them, and offset in height. one in relation to the other and each equipped with a rotation locking screw. This arrangement allows for balancing the machining forces, while also permitting reversible fixing of the adapter piece relative to on a spit. The present invention is now described with reference to the accompanying drawings, in which: - Figure 1 shows a front view of a tool according to the invention, with partial cuts along a plane passing through the spindle axis; - Figure 2 shows a cross-sectional view of the upper part of the tool, showing a fit in the extreme lower position of the shaft. machining, and therefore of the spindle. According to figure 1, a cylinder head of a heat engine with a valve seat (la) to be formed or ground, coaxially to a guide (lb) has been represented under the numerical reference 1. of valve stem. A tool according to the invention comprises the following main elements: - a housing (2) - a means of securing (63) or support of the housing (2) in relation to the cylinder head (1) to be machined - a sleeve (3) provided with a spherical orientation nut (3a), mounted inside the housing (2), this sleeve having a transverse bore (3b) whose axis passes through the center of the nut (3a) - two seats (4) and (5) of concave sphericity complementary to the spherical nut (3a), arranged inside the housing, on either side of the nut - a one-piece machining shaft (6), comprising, according to its height, a first part (6a). or spindle-forming hub, having a predetermined nominal diameter, and a second part (6b) of smaller diameter forming a pilot rod - a means (7) for locking the sleeve (3), in orientation and position as described below - a rotating machining tool (8), mounted at the end of the spindle (6a) on the side of the pilot rod (6b), by means of,on the one hand an adapter piece (9) fixed in rotation on the hub or spindle (6a), and on the other hand a tool holder device (10) mounted vertically on the adapter piece (9) - a means (11) of adjusting the height of the machining shaft (6), and consequently of the spindle (6a), relative to the sleeve (3); This means (11) is mounted on the sleeve (3), outside the housing (2), opposite the machining tool (8) - a means (12) for rotating the machining shaft (6), also outside the housing (2), above the height adjustment means (11), and opposite the machining tool (8). The housing (2), cylindrical in shape, whose axis passes through the center of the spherical nut (3a), comprises two parts mounted one on top of the other, namely a pot (13) having an external thread (13a), and a cover (14) in the form of a nut that can be screwed adjustablely onto the pot (13). From, On either side of the spherical nut (3a), the housing has two openings The two seats (4 and 5), apart from their concave spherical surface in contact with the nut (3a), are respectively located in the lid (14) and the pot (13); each of these openings allows the passage of the spindle (6a), with angular travel as described below. The lower seat (5) is movable in a reference plane on the flat internal surface (13b) located inside the pot (13), and therefore of the housing (2). The upper seat (4) rests freely on the spherical nut (3a). The lid or nut also includes an annular bearing (14b), located at the inside- eye of the housing (2). bearing against the upper seat during * smoothing (4), via a needle stop (15). The height adjustment means (11), or "depth adjustment," of the machining shaft (6) comprises, on the one hand, an adjustable nut (16), screwed onto a threaded sleeve (3c) belonging to the sleeve (3), and on the other hand, a coupling sleeve (17) for rotation with the hub (6a) of the machining shaft, mounted freely for rotation on the nut (16). This freedom of rotation is achieved by means of a radial rib (17a) belonging to the coupling sleeve (17), and two friction rings (18) on either side of the rib (17a), in a recess provided for this purpose in the nut (16). The radial rib (17a) has a threaded hole for the passage of a screw (19) for locking the coupling sleeve (17) against rotation relative to the hub (6a). The nut (16) has a radial bore. (16a), accessing the housing containing the rib (17a) of the coupling sleeve (17)); by rotating the nut (16) relative to the rib (17a), it is possible to bring the bore (16a) into coincidence with the head of the screw (19), and consequently to lock or unlock the latter reversibly, to free or lock the hub (6a) relative to the sleeve (17). The rotational drive means (12) consists of a crank whose head (20) is permanently mounted and locked in rotation on the coupling sleeve (17) by means of a flat (not shown). The head (20) has a transverse bore (20a), allowing the extraction of the machining shaft (6), as described below. As shown in Figure 1, the tooling parts located outside the housing (2), and on the side opposite the machining tool (8), namely the coupling sleeve (17) belonging to the height adjustment means (11) for the machining shaft (6), and the crank head (20), together define an extraction hole for the shaft (6), formed by the alignment of the bore (17b) of the sleeve (17) and the bore (20a) of the head (20), this along the axis of the transverse bore (3b) of the sleeve (3); the diameter of these different holes being at least equal to that of the hub (6a), outside the sheath (3). As for the means of securing (63) the housing (2), it consists of a support that can be removed from the housing. This support comprises, on one side, a base (63a) with holes (63b) for assembly studs on the cylinder head (1) to be machined, and on the other side, a table (63c) for receiving and securing the housing (2) with screws (65). In this way, it is possible to use the same tooling, and more specifically the different parts other than the support (63), for different cylinder heads. or motors. by adapting the support each time (63). The operation of a tool according to the invention can be deduced from the previous description, and can be briefly recalled according to the phases The following operating steps are performed: - by unscrewing the cover (14), the seats (4, 5) are loosened relative to each other, and the assembly consisting of the spherical nut (3a) in contact with the two seats (4, 5), relative to the sliding surface (13b), is freed; - by rotating the ring (22) counterclockwise, the seat (5) is centered, and consequently the nut (3a) and the upper seat (4) resting on it; by rotating the ring clockwise, the centered seat (5) is freed; - the tooling having been fixed to the cylinder head (1) by the support (63), the pilot rod (6b) is positioned in the guide (1b), which determines the orientation of the nut (3a) and its position relative to the sliding plane (13b) - by screwing on the cover (14), the stop (14b) simultaneously clamps the two seats (4 and 5) against the nut (3a) and against the internal surface (13b). From this locked position, by adjusting the nut (16), the machining tool (8) is brought into contact with the surface (la) to be ground. By rotating the crank, machining can then begin. the seat (the). According to the invention, the adapter piece (9) has the shape of a stirrup comprising two wings (9c, 9d), or annular plates, arranged perpendicularly with respect to the machining shaft (6), and connected to each other by a core (9e) or rigid part. These two wings have two central through threaded holes (9a, 9b), respectively arranged radially with respect to the axis of the machining shaft (6), making between They are at an angle of 180, offset in height from each other. and each equipped with a rotation-locking screw (80).

Claims

DEMANDS 1) Precision machining tooling according to claim 1 of the main patent, wherein an adapter piece (9) is mounted on the end of the hub or spindle (6a) of the machining shaft (6), on the side of the pilot rod (6b), and supports the rotating machining tool, said with the adapter piece fixed in rotation on the hub, while allowing- both the extraction of the single interchangeable machining shaft, through the extraction hole (17b, 20a) for parts located outside the housing (2), characterized in that the adapter piece (9) has two through threaded holes (9a, 9b), arranged radially with respect to the axis of the machining shaft (6), forming an angle of 180° between them, offset vertically from each other, and each equipped with a locking screw (80) rotating. 2) Tooling according to claim 1, characterized in that the adapter piece (9) has the shape of a stirrup comprising two wings (9c, 9d), arranged perpendicularly with respect to the machining shaft (6) and connected to each other by a web, the two wings comprising the two through threaded holes (9a. 9b) respectively.